For a vaccine to be effective against AIDS, it must be sufficiently antigenic to elicit a high level of protective antibodies. At present, it is expected that the preparations of the HIV itself or fractions or epitopes derived from it will not be sufficiently antigenic and will require the use of an adjuvant. Mineral oil- Arlacel A has been shown to be a very effective adjuvant, but concern has been expressed over possible long-term adverse effects, either of the immune system or by the development of malignancy. The purpose of this study is to ascertain whether this concern is real. In 1951-1953, 18,000 men were given influenza vaccine adjuvanted by a mixture of mineral oil and Arlacel A. To determine whether the use of this adjuvant may be associated with long-term adverse effects, the mortality experience of these men will be compared to that of 22,000 men who received a control inoculation of formalinized slaine solution. Deaths will be as certained by search of the Beneficiary Identification and Records Locator Subsystem (BIRLS) of the Veteran's Administration. An estimated 2,000 "matches" will be doubtful, and will be checked against the microfilm records at the St. Louis Records Center. Death certificates will be obtained from the VA; if not available there, then from the appropriate state. The deaths will be analyzed by time and cause, with principle interest in deaths related to malignancy or diseases of the immune system using the same criteria that had been used in earlier analyses carried out 9 and 17 years after vaccination. This study, carried out 33-35 years after vaccination, will cover the maximal expected induction period for malignant disease. If no differences in causes and times of death can be established between these two groups of men, it will be feasible to use the mineral oil-Arlacel A mixture as an adjuvant to HIV or split products or epitopes thereof.